Heat exchange roll



March 3, 1959 P. HOLD 2,875,985

HEAT EXCHANGE ROLL Filed Oct. 30, 1957 2 Sheets-Sheet 1 m; Ma

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ATTORNEYS March 3, 1959 P. HOLD 2,875,985

HEAT EXCHANGE ROLL Filed Oct. 30, 1957 2 Sheets-Sheet 2 I INVENTOR W ATTORNEYS United States Patent 2,875,985 HEAT EXCHANGE ROLL Peter Hold, Milford, Conn.,

ham Company, Incorporated, poration of Connecticut assignor to Farrel-Birming- Ansonia, -Conn., a cor- This invention relates to heat exchange rolls such as used, for example, in calendering plastics or like material, or in rolling thin sheets or films of metal or other materials.

In rolls employed for been a general object to effect heat the working surface of the roll and an internally circulating fluid, such as water, in a manner to bring about the maintenance of a uniform temperature throughout the working surface, but prior rolls provided with this aim in view have not accomplished this purpose satisfactorily and also have been open to certain other objections. The failure of previous rolls to bring about a uniform temperature throughout the working surface has been due to one or more conditions such as the fact that the journal such purposes, in the past, it has exchange between ends of the roll tend to affect the heat balance or the 9 fact that the material being processed does not always have a uniform eflect or temperature across the roll face. In addition, where the heat exchange medium progresses along generally lengthwise paths on or associated with the outer surface of the shell within the roll body or cylinder, the moving fluid is subjected to a temperature change and thereby creates a difierent effect at one end of the roll from that at the other end.

An object of the present invention is to overcome these obstacles and provide for maintenance of a uniform temperature throughout the working surface of the roll.

Another object is to provide for a condition where, for certain reasons, it is desired to have different temperatures at different parts of the working surface.

A further object is to furnish an effective and close control of the surface temperature of the roll in order to obtain a predictable and desirable roll temperature condition in cases where different temperatures are desired in different parts of the roll.

In the accompanying drawings:

Fig. l is a longitudinal section through a roll con structed in accordance with the invention;

Fig. 2 is an elevation of the internal shell as it appears before insertion into the roll cylinder;

Fig. 3 is a view of the blank used in forming the shell;

Fig. 4 shows in elevation a modified form of shell; and

Fig. 5 is a view of a blank used in making the shell portion of Fig. 4.

In the roll construction shown in Fig. 1, the outer part of the roll is made in three parts, i. e., a relatively heavy-walled cylinder open at opposite ends, and at these ends hollow journals or gudgeons, said journals or gudgeons being secured to the ends of the cylinder by screws or like fasteners. Within the cylinder part of the roll is a relatively light-walled shell, the length of which is substantially the same as that of the cylinder, said shell, however, being of tapered form, one end being of notably greater diameter than the other; this shell being provided with end heads each of which is connected to a circulating pipe that is located within the adjacent hollow journal. The fluid used for heat exchange is caused to impinge against the external surfaces of the end heads of the "ice shell and to progress lengthwise of the roll while in contact with the outer surface of the tapering shell body and the inner surface of the cylinder. Moreover, as the fluid moves generally lengthwise of the roll while in con tact with the tapering or conical body of the shell, it is caused to travel in a generally helical path by reason of its being confined to generally helical guide paths on the outer surface of the shell.

In the drawings, the main cylinder or roll body is indicated at 10, the hollow journals at 11 and 12, respectively, fastener screws for fastening the journals to the cylinder body at 13, the tapering or conical inner shell at 14, the left-hand bearing-enclosed pipe (Fig. 1) at 15, the right-hand bearing-enclosed pipe at 16, the left-hand end head for the shell at 17, and the right-hand end head for the shell at 18. The generally helical guide paths or channels on the outer surface of the shell body are in-: dicated at 19, these being created by providing the shell externally with helical ribs or fins 20.

The shell 14 has a relatively thin wall and it can be conveniently made of sheet metal. The blank has the form shown in Fig. 3, opposite edges being straight and divergent so that, when the blank is formed to create the tapered shell and when the divergent edges have been suitably interconnected as by welding, the shell will take the form shown in Fig. 2. The guiding ribs initially have the form shown at 20 in Fig. 3, but in the final shape of the shell these have the helical form shown in Fig. 2.

It will also be noted that the curved edges of the blank. are cut away, as shown in Fig. 3, to provide along each edge a series of notches or crenelations 21, these having the function of ports at the end edges of the shell which provide communication between the spaces externally of the end heads 17, 18 and the spaces extending generally lengthwise of the shell at its outside diameter. The heads of the shell are set in so as to be inwardly of the notches.

It will be noted from Fig. 1 that the heads 17, 18 are dished or cupped in such a way that they conform in a general way to the inner contour of the roll journals while leaving spaces externally of the heads.

The inner end of the left-hand pipe 15 (Fig. l) is fastened in an open socket on the head 17. In a similar manner, the pipe 16 has its inner open end fastened to the head 18. The pipe 15 is extended out of its associated roll bearing, but it will be observed that the pipe 16 is shorter and that the outer end of the bearing 12 is closed in a suitable manner, as by a plug 22. Both of the pipes 15 and 16 are of such size that exteriorly of these pipes longitudinal passages are provided in the roll bearings.

In the operation of the roll, fluid introduced into the outer end of the bearing 11 around the pipe 15 in a suitable manner (not shown) travels to the right (Fig. l) in the bearing and over the shell head 17 and through the notches 21 into the guide channels or passages between the helical ribs 20 so as to travel in helical paths from the smaller end of the shell to the larger end. At the larger end of the shell, this fluid enters the notches 21 and travels inwardly over the head 18 and progresses in an axial direction exteriorly of pipe 16. The end of thebearing 12 being closed oif, the fluid, by provision of a disk-like member 23 supporting the end of the pipe 16, is caused to flow in the direction of the arrows so that the fluid passes into pipe 16 into the interior of. the shell and out of the shell through the pipe 15.

It will be observed that in circulating through the roll in the manner above described, the heat exchange fluid, after passing over the left-hand shell head (Fig. 1), enters a space around the left-hand end of the shell which is considerably larger than the space extending around the shell at the opposite end. The body of fluid at the lefthand end of the roll is divided into parts by the helical the available working space,

ribs and has progressively less space as it moves along the shell while in contact with the shell and the cylinder, because of the continuously decreasing channel depth, being considerably more constricted at the exit end of the space than at the inlet end. This change in passage or channel area has important functions, one of which is that it compensates for the change taking place in the temperature of the cooling or heating medium, the result being that a more uniform temperature of the working surface of the roll is obtained. As in moving along, the heat exchange fluid is more restricted, there is also a distinct change in the turbulence of the medium. As the cross section of the channel is more restricted, the turbulence increases, and the rate of heat transfer increases correspondingly in ac cordance with hydrodynamic principles. Thus, in accordance with this invention, the previous tendenciesstanding in the way of uniform heating or cooling of the working surface are offset, and where such a condition is desired it is possible to secure much better results than heretofore.

There are also apt to arise special conditions where it is desirable to depart from the uniform heating or cooling of the working surface of the roll, and to provide the roll surface with concentration of heating or cooling in one or more portions. It should be pointed out that a roll structure of the type above described, but with some modifications, may be used to achieve this end, it being possible to obtain with such a structure a predictable and desirable roll surface condition as regards tempera.- ture. While in the foregoing example the inner shell has a straight taper, this can be modified, depending on the characteristics desired in the roll, as by changing the'diameter of the shell lengthwise by replacing the straight taper with a slight curve. 1

In the modified form shown in Figs. 4 and 5, the shell 24, instead of being tapered or conical, is cylindrical and the progressive change in the passages or channels extending generally lengthwise of the roll is brought about by changing the channel cross section laterally instead of depthwise. Here the ribs or fins on the shell are generally helical as before, but are so shaped and arranged that the channels or passages 26 decrease in width toward the outlet end of the shell. The blank for this shell is shown at 27, this being a fiat blank provided with fins or ribs 26 When the blank is rolled up to form the cylinder, the ribs are disposed on curves such as shown, for example, in Fig. 4. In Fig. 4, the wall of the cylinder enclosing the roll is indicated diagrammatically at 28 by broken lines.

It will be understood that the operation of this roll structure is similar to that first described, the chief difference being that, as the fluid moves generally lengthwise of the roll, its turbulence is increased toward the outlet end by the progressive narrowing of the channels. This narrowing arrangement of the channels will be apparent, especially from Fig. 5.

A further advantage of the roll structure herein described is that it is relatively simple and inexpensive. As far as the cylinder is concerned, this is similar in a general way to cylinder designs commonly used, and is inexpensive. The shell is constructed of relatively light metal which can be easily fabricated, and the piping connections to the shell are simple and can be provided at lowcost. Yet, while the construction in question has these. advantages, it is practical and has the necessary flexibility to achieve the desired end, namely, control ofv the temperature across the roll face, Where, in-a roll not provided with such heat exchange. control means,

the ends of the working face are either cooler or warmer than the center depending upon the operation.

It is to be understood that the foregoing description is by way of example only, and that various modifications and changes in the details may be made without departing from the involved principles and the scope of the claims.

What I claim is: l

1. In a heat exchange roll for calendering or rolling operations, the combination of a hollow cylinder having an outer working surface and provided with hollow end journals, an inner shell located within the cylinder and presenting between the cylinder wall and said shell a plurality of channels or passages for fluid moving generally lengthwise of the roll, said shell having end heads within the end portions of the cylinder defining with end heads provided on said cylinder radially and outwardly leading spaces leading to said channels or passages, and

means located within said hollow journals and cooperating with the end heads of said shell whereby fluid introduced into one of said journals will pass lengthwise of the roll between the said shell and the cylinder in one direction and will have a return flow in the opposite direction.

2. A roll structure as defined in claim 1, in which said channels or passages between the outer surface of the shell and the inner surface of the cylinder have less capacity in one portion of the roll than in another portion.

3. A structure as defined in claim 2, in which said channels or passages have less capacity at the outlet end than at the inlet end whereby at the outlet end increasing turbulence is provided.

4. A roll structure as longitudinal wall of the said channels or passages than at the inlet end.

5. A roll structure as defined in claim 3, in which said channels or passages are of greater depth at one end of the shell than at the other end.

6. In a heat exchange roll for calendering or rolling operations, the combination of a heavy-walled hollow cylinder, closures for the ends of said cylinder composed of end heads and hollow outstanding journals, a relatively thin-walled shell within said cylinder provided with a hollow body portion defining between it and the inner surface of the cylinder generally longitudinal passages for heat exchange fluid, the ends of the body of said shell being provided with notches communicating with said passages, said shell having inset heads providing radially outwardly leading spaces leading from the interior of said journals to said notches, communicating with an opening in one of said inset heads arrangedto return fiuid after it has passed over said shell so that such fluid can return through the shell, and means in the other journal communicating with an opening in the other inset head so as to carry oif such fluid, said last-named means comprising a member providing be tween it and its associated journal the inlet for the fluid into the cylinder.

7. A roll structure as defined in claim 6, in which the channels or passages between the body of the shell and the cylinder are of less capacity toward the outlet ends of said channels or passages to increase the turbulence of the fluid.

defined in claim 3, in which the shell is tapered and in which are shallower at the outlet end References Cited in the file of this patent UNITED STATES PATENTS means in one of said journals, 

